MicroRNA-429 promotes chemotherapeutic sensitivity of esophageal squamous cell carcinoma cells by inhibiting BMI-1 expression / 肿瘤

ABSTRACT

Objective: To study the expression of microRNA-429 (miR-429) in esophageal squamous cell carcinoma (ESCC) tissues and its relationship with the clinical characteristics and prognosis of patients, as well as to explore the regulatory effect of miR-429 on the chemotherapeutic sensitivity of ESCC cells and the underlying mechanism. Methods: The samples of tumor tissues and paracancerous tissues were collected from 60 cases of ESCC patients from January 2010 to December 2010. The expression level of miR-429 in tumor tissues and paracancerous tissues was detected by real-time fluorescent quantitative PCR, as well as its relationship with the clinical feathers of ESCC patients was analyzed. After the miR-429 mimic or miR-429 inhibitor was transfetcted into Eca109 and TE-13 cells, the proliferation and chemotherapy sensitivity of ESCC cells were measured by MTT assay, the apoptosis of ESCC cells treated with cisplatin (CDDP) was detected by FCM. A dual-luciferase reporter assay was performed to detect whether B-cell specific moloney murine leukemia virus insertion site-1 (Bmi-1) was a target gene of miR-429. The expressions of Bmi-1 and P-glycoprotein (P-gp) proteins in ESCC cells were analyzed by Western blotting. Results: The expression level of miR-429 in ESCC tissues was significantly higher than that in the paracancerous tissues (P < 0.01). For the ESCC tissues with miR-429 low expression, the size of tumor was bigger, the clinical stage of tumor was later, the lymph node metastasis was more likely to occure, and the survival time of ESCC patients was shorter as compared with the miR-429 higher expression group. After overexpressing miR-429, the proliferation viability of Eca109 and TE-13 cells were suppressed obviously, the sensitivity to CDDP was enhanced, the apoptosis rate was increased, while the expression levels of Bmi-1 and P-gp were significantly down-regulated (all P < 0.05). After blocking miR-429 expression, the proliferation viability of Eca109 and TE-13 cells were promoted obviously, the sensitivity to CDDP was weakened, the apoptosis rate was decreased, while the expression levels of Bmi-1 and P-gp were significantly up-regulated (all P < 0.05). In addition, the result of dual-luciferase reporter assay further confirmed that Bmi-1 gene was a target of miR-429, and the expressions of Bmi-1 and miR-429 were negative correlated (r ＝-0.340 4, P < 0.05). Conclusion: The ESCC patients with lower miR-429 expression in tumor tissues frequently have a worse clinical outcome and poorer prognosis. Furthermore, miR-429 can improve the sensitivity of ESCC cells to CDDP, and its mechanism may be associated with the regulation of target gene Bmi-1 expression.